Genetic variations in interleukin 28B (IL28B) have been strongly associated with a sustained virological response (SVR) in European and African-American patients. Genetic variation of IL28B was investigated in healthy controls and chronic hepatitis C (CHC) patients, and the treatment response in the CHC patients was analyzed according to IL28B polymorphism in the Korean population.
IL28B polymorphisms (rs12979860 and rs8099917) were studied in 200 healthy controls and in 167 CHC patients who were treated with peginterferon-α and ribavirin.
The prevalence of rs12979860 in healthy controls is as follows: the CC-genotype was 88.5%, the CT-genotype was 11.5%, and the TT-genotype was not found. The prevalence of rs8099917 in healthy controls is as follows: the TT-genotype was 89.5%, the TG-genotype was 10.5%, and the GG-genotype was not found. The CC-genotype of rs12979860 and the TT-genotype of rs8099917 were found to be closely related (linkage disequilibrium; D′=1.0, χ2=0.9082). In 106 CHC patients treated with peginterferon and ribavirin, the SVR was 67.2% (n=58) for 1b, 91.6% (n=47) for 2a. In hepatitis C virus (HCV) genotype 1b with respect to rs12979860, the SVR in CC-genotype was 72.9% and that in CT-genotype was 40.0%. On investigating predictive factors for SVR, pretreatment low-HCV RNA levels, HCV genotype non-1, early virological response, and also the IL28B CC-genotype for rs12979860 were good indicators of an SVR.
In Korea, genetic variation of IL28B is different from that in western countries in view of high prevalence of rs12979860 CC-genotype. It seems likely that a high SVR in Korean patients with genotype 1 CHC patients is due to the genetic polymorphism in IL28B.